8mm Forum: Lubricating plastic gears

This is topic Lubricating plastic gears in forum 8mm Forum at 8mm Forum.

To visit this topic, use this URL:
https://8mmforum.film-tech.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=000626

Posted by Mike Peckham (Member # 16) on July 17, 2004, 03:45 AM:

My recently aquired Elmo SP projector was suffering from years of lying dorment in a box and with use is slowly coming to life again. I was looking at the plastic gears in the back and can see that they have been greased up [probably in the factory] and it occurs to me that after 30 years it might be prudent to apply some new grease. Thing is, I'm not sure what sort of grease it is safe to use on plastic parts as I'm pretty certain that petrol based lubricants and plastic parts don't mix! Is that right?

So what should I use? Any ideas chaps?

Thanks

Mike

Posted by Tony Milman (Member # 7) on July 17, 2004, 05:39 AM:

Mike, I believe that a lithium based grease (think it is called white grease) is safe for plastic parts. The one thing to avoid is anything like 3 in one or wd40.

Tony

Posted by Mike Peckham (Member # 16) on July 17, 2004, 06:07 AM:

Thanks Tony, any idea where I can get some? I've just checked Maplins site but can't find any on there but I'm not sure how it would be listed.

Mike

Posted by Tony Milman (Member # 7) on July 17, 2004, 07:17 AM:

Mike, I think
you will find it at most car accessory shops. I think you can use a standard high melting point lithium based grease (that is what I use) but I am told that the specific white grease is the ultimate.

If you search under yahoo for white grease it lists a host of sites. For those who want technical information go to:

http://www.lubricant.co.uk/grease.html

Posted by Mike Peckham (Member # 16) on July 17, 2004, 07:28 AM:

Thanks Tony, I'll be off to Halfords this afternoon [Wink]

.

Mike

Posted by Tony Milman (Member # 7) on July 17, 2004, 07:39 AM:

Lucky you, I am off to Devon and running late! [Cool]

Posted by David Park (Member # 123) on July 17, 2004, 11:47 AM:

Yes I was adised to use this same type of grease in the 16mm forum.
I had to go to our local Car Parts Trade outlet in order to get it. Allthough I'm not trade they were very helpfull and helped me find it on the shelves and supplied me.

Posted by Tim Christian (Member # 48) on July 17, 2004, 12:44 PM:

Electrolube SPG Special Plastics Grease is used for video recorder gears etc. Farnell stock it in 25 g syringes (very handy) - Part No. 725-626. Not cheap but a little goes a long way.

Posted by Kevin Faulkner (Member # 6) on July 17, 2004, 02:48 PM:

The grease I use is Castrol LM or Heavy grease. These tend to look like the grease that Elmo used on the machines. I did try some Lith based white grease but because of the grease Elmo used I found that it wouldnt stick to the gears and just deposited itself round the internals of the machine so I didnt carry on with the stuff. My thoughts were that if it wouldnt mix with the existing grease then it was the wrong stuff.

Kev.

Posted by Tim Christian (Member # 48) on July 17, 2004, 04:45 PM:

The use of mineral-based grease on plastics is a no-no. Over a couple of years, depending on the plastic, these parts will gradually embrittle and eventually simply fall apart.

Stick to the stuff used by the trade.

Posted by Tony Milman (Member # 7) on July 22, 2004, 12:27 AM:

Kev, Tim

Being ignorant on such matters, is the Castrol LM grease a "mineral" grease? How long have you applied it for Kev and with what results?

Tony

Posted by Trevor Adams (Member # 42) on July 22, 2004, 04:57 AM:

How about Moly paste?Trev

Posted by Mike Peckham (Member # 16) on July 23, 2004, 01:27 AM:

Trev

Moly Paste?

Mike

Posted by Tony Milman (Member # 7) on July 23, 2004, 01:39 AM:

Mike

A nice Girl Trev knows from South Island

Tony [Wink]

Posted by Tim Christian (Member # 48) on July 23, 2004, 02:05 AM:

Alternatives to the type of grease I mentioned above is Dow Corning PG 30. This was advised by UK agents R.W. Greef (01 384 897969).

A problem with plastic gear is that of identifying the type of plastic, thus a grease suitable for even the most susceptible types should be chosen. Effects of mineral lubricants on plastic gears vary from total disintegration (ABS/Polystyrene) in less than a year to swellling and/or softening with nylon.

Posted by Paul Adsett (Member # 25) on July 23, 2004, 09:59 AM:

The GS1200 Service Manual does not show any direct lubrication of the plastic gears. The following lubrication is indicated:
1)The main brass worm gear, which contacts plastic gearing, is called out to be lubricated with Shell Alvavia Grease 2. This is a mineral base grease with Lithium thickner. Presumably this grease also must spread to the surface of the plastic gears as a result of contact with the brass worm gear.
2) The claw cam surface is required to be lubricated with Molykote EP. This is a high pressure grease with molybdenum additive.

3) For other areas, shafts, rollers etc, they call out Veddle 20-40 oil and Daphne 44 oil.

I recently greased up my GS gears with Exxon Lidok 2 EP general purpose grease, and am now questioning whether to strip down and re-lube with a different grease. I did use a grey Moly EP grease for the shuttle cam.
Mike has certainly raised a very interesting (if very difficult) question, which could affect the life of our projectors if we don't all use the right lube.

Posted by Kevin Faulkner (Member # 6) on July 24, 2004, 04:43 AM:

In theory the cogs dont really need grease. I think it's applied to keep the whole thing quiet.
Time where can we get some of the grease (non mineral) that you use?

Kev.

Posted by Tim Christian (Member # 48) on July 24, 2004, 06:24 AM:

I get my Electrolube from

Farnell

via a local wholesaler.

As I mentioned above, it is worth talking to he technical service guys at R.W. Greeff (01 384 897969). They deal in Dow-Corning products.

web page

Yes, ideally nylon/delrin etc gears need no lubricant. However, grease does make machines a lot quieter - especially older ones.

Posted by Tony Milman (Member # 7) on July 25, 2004, 03:18 AM:

What should you use to remove the existing grease without causing further damage?

Tony

Posted by Tim Christian (Member # 48) on July 25, 2004, 03:25 AM:

Paraffin or white spirit - but dry properly.

Posted by Daryl C. W. O'Shea (Member # 1) on July 25, 2004, 11:33 PM:

Maybe a plastic safe silicone lubricant would be an alternative.

Posted by Ronnie Coeuhant (Member # 143) on July 26, 2004, 09:53 AM:

In the US, you can get Silicone lubricants below - similar to what they use in industrial robotics for electronics manufacturing:

SSP Lubricant

Cheap at about $10 for 5 ounce and it can be used for metal-to-metal and plastics-to-metal.

Posted by Tim Christian (Member # 48) on July 26, 2004, 10:04 AM:

The problem we have is that we are trying to extend the life of equipment beyond its design useful life. I use the lubricant specified above because a local friend who maintains equipment with plastic gears has used it for 20 years without problems.

If you ask lubricant manufacturers who claim 'plastic safe' if their product is safe for, say, 20 years they will usually start to hedge their bets. Most of the time, they say, 'Ask the material supplier.' This is a major problem because you are never sure with a 30 year old projector who made the bits - certainly not the material.

Another good question is: 'Is this safe on gelatin and cellulose acetate for 75 years? If anyone gets a firm answer, please post it here!

Posted by Paul Adsett (Member # 25) on July 26, 2004, 10:06 AM:

The main problem with using ANY silicone products in projectors , is the potential for silicones to migrate to optical surfaces. I have been in the Laser industry for 30 years, and Silicones have long ago been banned from use in our facility because there is absolutely no way of cleaning silicones off any type of optical surface. Clearly, laser optics are much more critical than movie projection lenses, but I would think there would still be a concern about the stuff migrating around the machine, getting on the film path and optics.

Posted by Tony Milman (Member # 7) on July 26, 2004, 12:16 PM:

Paul

If you have silicon on your optics can you tell? Is it visible to the naked eye? What about furniture polish containing silicon is that an issue as well?

Tony

Posted by Paul Adsett (Member # 25) on July 26, 2004, 06:05 PM:

Hi Tony,
I'm not sure that a very light coating of silicone would be visible to the naked eye. The main danger is the lens coatings, since even a very light layer of silicone would screw up the anti-reflection properties of the coating, manifesting itself as increased light light loss and loss of image contrast.
Must confess I had not thought about the furniture polish. The stuff I use (Favor) for polishing up the projector does not mention any silicone content. Here again Tony, I do not wish to be an alarmist. As I said, the situation with high power laser optics is quite different from visible light optics. But I think in general it is probably preferable to avoid silicone greases around any optical system.

UBB.classic^TM 6.3.1.2